Calender and method for controlling such a calender

ABSTRACT

A calender includes a rotatable roller, and a belt co-acting with the roller with a determined belt pressure. At least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender. The calender also includes heating means for heating the fluid and/or the roller, control means for controlling the heating means and/or the belt pressure and/or the contact time, and a database for storing data. The control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in the database, before and/or during throughfeed of the material. A set with a plurality of such calenders and a method for controlling such a calender.

The invention relates to a calender, comprising:

-   -   a rotatable roller, which roller is hollow and thereby defines         an internal space which can be filled at least partially or is         filled at least partially with a heatable fluid, such as oil or         air;     -   a belt, co-acting with the roller, with a determined belt         pressure, wherein a material for feeding through the calender is         situated between the roller and the belt for a determined         contact time during throughfeed through the calender;     -   heating means for heating the fluid and/or the roller, which         heating means are optionally disposed in the internal space; and     -   one or more control means for controlling the heating means         and/or the belt pressure and/or the contact time.

Such a calender is per se known. Particularly known are different types of calender. There is thus for instance a type of calender which is used for throughfeed of a material, wherein a print is fixated on the material if the material already had a print printed thereon prior to throughfeed through the calender, or is transferred thereto from a so-called transfer paper if the material did not yet have a print prior to throughfeed through the calender. Such a calender can also be referred to as a device for transfer and/or fixation. Another type of calender is a laminating calender or laminating device, wherein multiple materials are fed through the calender and are here bonded to each other, i.e. laminated. The material or the materials can be any desired and/or suitable material, such as for instance textile.

The calendering process takes place under the influence of heat. The heat comes from the heating means which heat the fluid, such as oil or air, whereby the roller is heated by the heated fluid, and optionally in that the heating means heat the roller directly, for instance by radiation. Direct heating of the roller by for instance radiation takes place particularly in the case of air-filled rollers. Indirect heating by the heating means via the heatable fluid takes place particularly in the case of both oil-filled and air-filled rollers. The heating can be set as desired, particularly by controlling the heating means in desired manner Controlling the heating means can for instance comprise of controlling a power of the heating means.

The calendering process further takes place under the influence of pressure. The pressure is provided by said belt and can be set as desired, particularly by controlling the belt pressure in suitable manner, more particularly by tightening the belt or arranging the belt more loosely, whereby the pressure is respectively increased and reduced.

In addition to the heat and pressure, the contact time, i.e. the amount of time that the at least one material is in direct or indirect contact with the roller, can also be particularly important for the calendering process. The contact time can be set as desired, for instance by selecting a rotation speed of the roller. Controlling of the contact time can therefore alternatively or additionally be formulated as controlling of the roller, more particularly controlling of the rotation speed of the roller, still more particularly controlling of drive means for rotating driving of the roller.

For the sake of simplicity the one or more control means are also referred to below as “the control means”.

The control means control the heating means and/or the belt pressure and/or the contact time such that a desired calendering process should be achieved. It has however been found by applicant that, despite this control, the result of the calendering process is not always fully as desired and/or consistent. It is an object of the invention to at least reduce or preferably obviate this drawback.

This object can be achieved by means of a calender of the type stated in the preamble, which is characterized according to the invention by:

a database in which at least one of the following data is stored, optionally periodically:

-   -   a measured outer periphery temperature of the roller;     -   a measured fluid temperature;     -   the contact time;     -   the belt pressure;     -   a power of the heating means;     -   number of revolutions of the roller since the start of a         calendering process;     -   at least one property of the at least one material being fed         through the calender;     -   at least one property of a transfer paper optionally being fed         through the calender;     -   an ambient temperature;     -   an air humidity;     -   which calender is used;     -   a power of drive means of the calender;     -   at least one property of a belt of the calender,

and the one or more control means are further configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in the database, before and/or during throughfeed of the material.

It has been found by applicant that it is advantageous to store one or preferably more of the above stated parameters in a database so that the control means can control the heating means and/or the belt pressure and/or the contact time on the basis of these data. These data can particularly be stored for calendering processes in which a good and/or consistent calendering result has been achieved, and controlling can then take place on the basis thereof so that a good process can be substantially repeated. By collecting sufficient data from, preferably, a plurality of calendering processes with the same or different calenders and recording these data in a database a calender can be controlled properly on the basis of these data.

The parameters are preferably recorded in the database frequently, for instance every 10 seconds or, if desired, less or more often. In order to keep the amount of data limited it is possible to only register changes.

Because the control means are configured here to control the heating means and/or the belt pressure and/or the contact time before and/or during throughfeed of the material, a feed forward is achieved, whereby it is possible during the process to anticipate the influence of changes in one or more of the parameters which are stored in the database.

The use of each of said parameters being registered in the database will be elucidated below. It will be apparent that one or more of these parameters, in any suitable and/or desired combination, can be stored and that controlling can take place on the basis of these one or more parameters.

As elucidated above, the contact time, the belt pressure and the power of the heating means influence the calendering process, and the calender can be controlled accordingly. It is thereby advantageous to store the settings of the contact time, i.e. the rotation speed of the calender, the belt pressure and the power of the heating means, preferably periodically, so that control can take place on the basis of these stored data in subsequent calendering processes.

In addition to these parameters, it can be particularly important to store in the database a measured outer periphery temperature of the roller, which temperature can influence a calendering process to a significant extent, and to control the heating means and/or the belt pressure and/or the contact time also on the basis of the measured outer periphery temperature.

A first temperature sensor can be provided for the purpose of measuring the outer periphery temperature of the roller. This measures at the external surface of the roller, more specifically at a position where the material comes into contact with the roller and/or in or close to the centre of the roller and/or in the area lying at a distance of at least 20 centimetres from the edges of the roller. When only one first temperature sensor is provided, it is preferably arranged in or close to the centre of the roller.

A measured fluid temperature of the roller can further also be important, particularly because this can be related to the outer periphery temperature of the roller and because it can provide insight into how at least the heating means must be controlled. It can therefore also be useful to store this measured fluid temperature in the database and to control the heating means and/or the belt pressure and/or the contact time also on the basis of the measured outer periphery temperature.

A second temperature sensor can be provided for the purpose of measuring the fluid temperature.

Recording data about the number of revolutions of the roller since the start of a calendering process makes it possible to determine the number of revolutions starting from which a good result can be obtained, and/or when the heating means can be switched off at the end of a calendering process. If desired, the device can comprise means for making it known that a calendering process can be started, for instance visually by means of lighting.

Properties of the material, for instance type of material and/or (specific) weight, usually expressed in gram/m², often determine a heat absorption by the material and thereby how the control means must control the heating means and/or the belt pressure and/or the contact time. Registering the power of the heating means in combination with registering the at least one property of the material can provide insight into this heat absorption, for instance by registering the amount of energy, i.e. power, required to keep the outer periphery of the roller at a determined temperature without throughfeed of a determined material, relative to the amount of energy required during throughfeed of a determined material. This information can be used to select a determined power for the heating means even before a determined material is actually fed through. The operator can enter which material will be fed through, for instance via an interface of the device. For a heavier material it is for instance possible to select a greater power than for a lighter material, since the heat absorption of a heavier material is usually higher than for a lighter material. This can be particularly advantageous when starting up a calendering process and when switching between different materials.

Properties of the transfer paper, for instance humidity and/or type of material and/or (specific) weight, usually expressed in gram/m², can determine a heat absorption by the transfer paper. By optionally also registering this, it is possible also to control on the basis hereof.

The ambient temperature can influence the energy loss of the roller. The heating means and/or the belt pressure and/or the contact time can therefore be controlled in desired manner on the basis of a measured ambient temperature, for instance by increasing a power of the heating means when the ambient temperature is lower than a determined value, and vice versa.

An ambient temperature sensor can be provided for the purpose of measuring the ambient temperature.

The air humidity can likewise influence the energy consumption of the roller. An air humidity sensor can be provided for the purpose of measuring the air humidity.

Which calender is used can likewise influence a desired setting. This can comprise both the type of calender, and which calender is used from among calenders of the same type.

The power of drive means of the calender can likewise be of influence.

The belt of the calender can absorb heat. When the at least one property of the belt is known, it is for instance known how great the energy absorption of the belt in question can be, whereby the heating means can be controlled on the basis of these data in order to improve the process still further. Type of material and/or age of the belt can for instance be determining factors.

As elucidated above, it is possible to register the amount of energy, i.e. power, required to keep the outer periphery of the roller at a determined temperature without throughfeed of a determined material and with throughfeed of a determined material. This registered energy provides insight into how much energy leaks away without throughfeed of material, for instance due to heat absorption of the belt and/or due to radiation and/or due to a cold environment, and with throughfeed of material, due to heat absorption by the material. A more accurate process can be obtained by registering this energy by means of registering the power of the heating means and recording said parameters and controlling the heating means and/or the belt pressure and/or the contact time on the basis thereof.

In another embodiment of the device according to the invention the control means are configured to determine before and/or during throughfeed of the material, on the basis of at least periodically recorded settings of the heating means and/or the belt pressure and/or the contact time of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material, how the heating means and/or the belt pressure and/or the contact time must be set, and to control the heating means and/or the belt pressure and/or the contact time in the determined manner.

A prior, successful process can be repeated by collecting said settings in the database, particularly for successful calendering processes, and optionally the other parameters as stated above, and by controlling the calender on the basis of these data before and/or during throughfeed of the material.

In another embodiment of the device according to the invention the database and the control means are connected or at least connectable to each other, optionally wirelessly, for instance via a computer network, such as for instance the Internet.

In practical manner there is a connection between the database and the control means. This connection preferably takes place via a computer network. This has the advantage that the data as collected on the basis of a plurality of calenders according to the invention can be collected in one database. Because this one database contains all data relating to the operation of a plurality of calenders, even more data are available, which can result in a more reliable operation of the calender with a view to a good quality. Central processing of these data in one database moreover has the advantage that these data can be secured more easily and thereby more cheaply. Wireless connections are preferred here because they are very flexible and have sufficient bandwidth for the amount of data to be transferred.

It is possible for a connection between the database and the device to drop out at least temporarily. It can be advantageous for the control means to be configured to control the flow influencing means and/or the heating means and/or the belt pressure and/or the contact time on the basis of average values, more particularly on the basis of average values for a determined fed-through material, as soon as this happens.

The heating means can be disposed outside the internal space of the roller, but can alternatively also be disposed in the internal space. Disposing or placing in the internal space makes the calender more compact, and further makes it possible to heat the fluid in the vicinity of the peripheral wall of the roller and/or to heat the roller directly, so that a relatively rapid heating of the roller can take place. In an embodiment the heating means can be embodied as electrical heating element, such as for instance a glowing or radiating heating element.

The fluid can be any suitable fluid but is preferably oil or air. It is preferably contained in a system which is closed at least to said fluid and comprises at least the internal space of the roller, and optionally for instance an expansion tank connected via at least one conduit to the internal space. And oil, such as particularly thermal oil, for instance mineral thermal oil or synthetic thermal oil, has a heat transfer coefficient suitable for the invention and can moreover be heatable to a relatively high temperature without this greatly reducing the lifespan. Oil can alternatively or additionally have a large heat capacity. Air has the great advantage that it keeps the calender relatively simple and is able to increase or reduce the temperature of the roller relatively quickly.

The roller will typically be a cylindrical body. During operation this body will generally be rotated about its rotation axis, in practical manner its width axis, at a desired rotation speed by means of drive means, wherein the substrate is carried over the outer periphery.

The control means are preferably embodied as an electronic device with at least one input and one output and a processor, such as a microprocessor, which device controls the at least one output on the basis of the information at the at least one input, for instance a programmable logic controller (PLC).

The invention also relates to a set with a plurality of calenders as described above, wherein the control means of at least one of the calenders are configured to control the heating means and/or the belt pressure and/or the contact time of that one calender on the basis of optionally periodically registered data of calendering processes performed with the calenders of the set.

Said one calender is preferably a calender of the set other than the calender of which the data are registered. In this way the progression of the process in one or more other calenders can be used to efficiently control this one calender.

The invention further relates to a method for controlling a calender as described above on the basis of one or more examples, in any random combination, which method comprises the following steps, to be performed in any suitable order, of:

a) controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means on the basis of at least one of the data contained in the database, before and/or during throughfeed of the material.

An advantage hereof is elucidated on the basis of the device according to the invention.

Step a) is preferably performed regularly, preferably almost continuously.

In an exemplary appointment of the method according to the invention step a) can be performed by determining on the basis of at least periodically recorded settings of the heating means and/or the belt pressure and/or the contact time of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time must be set, and by controlling the heating means and/or the belt pressure and/or the contact time in the determined manner.

An advantage hereof is elucidated on the basis of the device according to the invention.

In yet another embodiment of the method according to the invention it comprises the steps of:

b) observing that a connection with the database has dropped out;

c) controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means on the basis of average values while the connection has dropped out.

Step c) can be performed instead of step a) at least temporarily, particularly for as long as the connection with the database is absent.

In yet another embodiment of the method according to the invention it comprises the steps of:

d) entering a material for feeding through the calender;

e) setting the heating means and/or the belt pressure and/or contact time on the basis of at least one property of the material entered in step d).

As elucidated above, the at least one property of the material, particularly the (specific) weight thereof, usually expressed in gram/m², can determine a required power of the heating means and/or the belt pressure and/or the contact time. Entering the material in step d), such as for instance entering one or more of a name, type or at least one property of the material, for instance by an operator via an interface of the calender, enables the calender to be set thereto, preferably even before the material is actually fed through. If it is for instance known that the material has a determined heat absorption, the power of the heating means can already be set, more particularly already be increased or decreased, in accordance with the heat absorption of the material. This can be useful at the start of a calendering process or during switching of materials for feeding through. At the start of a calendering process the power can be increased relative to a state in which no material is supplied, wherein the increase is for instance in accordance with the weight of the material. A power of the heating means can for instance alternatively or additionally be increased when a material with a higher weight is switched to, and vice versa, wherein the increase or reduction is in accordance with for instance the weight of the material. The type of material can also play a part here, and thereby also determine for instance the setting of the heating means.

In this method it can further be advantageous to wait until the calender is ready for throughfeed of the material for feeding through. For this purpose the method can comprise the steps of:

f) generating a signal when the calender is ready for throughfeed of the material entered in step d);

g) feeding through the material after the signal has been generated.

The signal can be any suitable signal, such as a visual or auditory signal. A visual signal can for instance comprise an illumination, for instance a red light when the material cannot yet be fed through, and a green light as soon as the material can be fed through.

In an embodiment of the invention the calender can comprise means for generating a signal, such as for instance said illumination.

The steps of the method can be performed in any suitable order.

If desired, one or more of the described steps can be repeated and/or be performed periodically.

The invention will be further elucidated with reference to the accompanying figures, in which:

FIG. 1 shows schematically a set with a plurality of calenders according to an embodiment of the invention;

FIG. 2 shows schematically the steps of a method according to an embodiment of the invention.

FIG. 1 shows schematically a number of calenders 1-5 according to the invention, each provided with one or more control means (not shown). Calenders 1-5 can be accommodated at the same or at different production sites. These calenders are connected via respective connections 6-10, which run via a network such as the Internet 11, to a database 12, which is also connected to the Internet 11. Calenders 1-5, or at least a part thereof, are configured to store via respective connections 6-10 running via Internet 11 at least one parameter in respect of the arrangement of calenders 1-5 in the database, such as for instance a measured outer periphery temperature of the roller of calenders 1-5, a measured fluid temperature in calenders 1-5, the contact time, the belt pressure, a power of the heating means of calenders 1-5, number of revolutions of the roller of calenders 1-5 since the start of a calendering process, at least one property of the at least one material being fed through calenders 1-5, at least one property of a transfer paper optionally being fed through calenders 1-5, an ambient temperature around calenders 1-5, which calender 1-5 is being used, a power of drive means of the calender 1-5 and/or at least one property of a belt of calenders 1-5. The calenders 1-5 which are provided with one or more control means are further also configured to control the heating means and/or the belt pressure and/or the contact time of calenders 1-5 on the basis of at least one of the data contained in database 12.

The control means of calender 1 are configured to control the heating means and/or the belt pressure and/or the contact time of calender 1 on the basis of optionally periodically registered data of calendering processes performed with the set of calenders 1-5, wherein this can particularly involve/relate to the other calenders 2-5, before and/or during throughfeed of a material through calender 1.

A method 100 which can be performed with one or more of the calenders 1-5 is shown in FIG. 2. This method comprises the step 101 of controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means of calenders 1-5 on the basis of at least one of the data contained in database 12, for instance for the purpose of bringing calenders 1-5 into a stationary state. It is possible here for this step to be performed by determining on the basis of at least periodically recorded settings of the heating means and/or the belt pressure and/or the contact time of a plurality of prior calendering processes performed with calenders 1-5, or a part thereof, and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time of calenders 1-5 must be set, and by controlling the heating means and/or the belt pressure and/or the contact time of calenders 1-5 in the determined manner.

The method then comprises the step 102 of entering a material for feeding through the calender 1-5, for instance by an operator via an interface of the calender 1-5, and the step 103 of setting the heating means and/or the belt pressure and/or the contact time on the basis of at least one property of the material entered in step 102, whereby the calender 1-5 is for instance brought from the stationary state into an operative state in which the material can be entered. The method here preferably comprises the step 104 of generating a signal when the calender 1-5 is ready for throughfeed of the material entered in step 102, after which the material is actually fed through in step 105.

The possible dropping out of the respective connection 6-10 is preferably taken into consideration in the method. When it is observed during one of these steps 101-105 that a connection, such as the respective connection 6-10, to database 12 drops out, as shown in step 106, the one or more control means will preferably control the heating means and/or the belt pressure and/or the contact time in step 107 on the basis of average values until the connection has been restored, as shown in step 108, after which the control on the basis of at least one of the data contained in database 12 is returned to.

It is noted that the steps 101-105 are shown in sequential order, but that the steps can be performed in any suitable order and/or that, if desired, one or more steps can be repeated. It is thus possible to additionally or moreover alternatively perform the step 101 of controlling during the throughfeed step 105.

Although the invention is elucidated above on the basis of a number of specific examples and embodiments, the invention is not limited thereto. The invention instead also covers the subject matter defined by the following claims. 

1. A calender, comprising: a rotatable roller, which roller is hollow and thereby defines an internal space which can be filled at least partially or is filled at least partially with a heatable fluid, such as oil or air; a belt, co-acting with the roller, with a determined belt pressure, wherein at least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender; heating means for heating the fluid and/or the roller, which heating means are disposed in the internal space; one or more control means for controlling the heating means and/or the belt pressure and/or the contact time, characterized by a database in which at least one of the following data is stored, periodically: a measured outer periphery temperature of the roller; a measured fluid temperature; the contact time; the belt pressure; a power of the heating means; number of revolutions of the roller since the start of a calendering process; at least one property of the at least one material being fed through the calender; at least one property of a transfer paper being fed through the calender; an ambient temperature; an air humidity; which calender is used; a power of drive means of the calender; at least one property of a belt of the calender, and the one or more control means are further configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in the database, before and/or during throughfeed of the material.
 2. The calender according to claim 1, wherein the control means are configured to determine before and/or during throughfeed of the material, on the basis of at least periodically recorded settings of the heating means and/or the belt pressure and/or the contact time of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material, how the heating means and/or the belt pressure and/or the contact time must be set, and to control the heating means and/or the belt pressure and/or the contact time in the determined manner.
 3. The calender according to claim 1, wherein the control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the ambient temperature.
 4. The calender according to claim 1, wherein the database and the control means are connected or at least connectable to each other, wirelessly or via a computer network.
 5. The calender according to claim 1, wherein the control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of average values when a connection with the database drops out.
 6. A set with a plurality of calenders according to claim 1, wherein the control means of at least one of the calenders are configured to control the heating means and/or the belt pressure and/or the contact time of that one calender on the basis of periodically registered data of calendering processes performed with the calenders of the set.
 7. The set according to claim 6, wherein said one calender is a calender of the set other than the calender of which the data are registered.
 8. A method for controlling a calender according to claim 1, which method comprises the following steps of: a) controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means on the basis of at least one of the data contained in the database, before and/or during throughfeed of the material.
 9. The method according to claim 8, wherein step a) is performed by determining on the basis of at least periodically recorded settings of the heating means and/or the belt pressure and/or the contact time of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time must be set, and by controlling the heating means and/or the belt pressure and/or the contact time in the determined manner.
 10. The method according to claim 8, wherein step a) is performed by controlling the heating means and/or the belt pressure and/or the contact time on the basis of the ambient temperature.
 11. The method according to claim 8, comprising the steps of: b) observing that a connection with the database has dropped out; and c) controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means on the basis of average values while the connection has dropped out.
 12. The method according to claim 8, comprising the steps of: d) entering a material for feeding through the calender; e) setting the heating means and/or the belt pressure and/or contact time on the basis of at least one property of the material entered in step d).
 13. The method according to claim 12, comprising the steps of: f) generating a signal when the calender is ready for throughfeed of the material entered in step d); and g) feeding through the material after the signal has been generated. 